Chelsea showing signs of progress with Guus Hiddink, but how far can they go?

LONDON -- Just over two weeks into his return as manager, there's been no grand gesture so far from Guus Hiddink to the Chelsea squad, nothing to signal massive change. There have only been little, notable moments.

This subtle approach is most evident during training. According to sources at the club's Cobham base, Hiddink spends the majority of sessions observing and leaves most of the work to his back-up staff. Yet that changes when he spots something he feels needs specific instruction. Then, he will stop the session and offer some tactical insight, something that subtly changes the approach.

These are small steps, but Chelsea showed more of their old swagger in a 3-0 win against Crystal Palace on Sunday. Indeed, it was their most expansive attacking performance since the 5-0 win at Swansea City on Jan. 17, 2015.

The question is simple: does the improved performance reflect a tactical change, a mental one, or a mixture of both?

Of course, the Palace match was only one game, and it would be dangerous to draw too many conclusions from that, but the multitude of changes was still striking. It wasn't just that so many Chelsea players were individually expressing themselves again, it was that they were combining so exquisitely.

The brilliant, if complex first goal seemed a particular spark of life. John Obi Mikel fed Cesc Fabregas before he, in turn, released it to Diego Costa. The crucial factor here was how Costa's run opened up play. From there, it was an easy pass to Oscar for the close-range finish.

It had been a long while since Chelsea have put something like that together and a long while since the attackers -- especially Fabregas -- have had such a range of options with which to open up opposition defences.

From there, the way Hiddink's side grew in confidence while repeating such moves suggested something had been built on the training ground. It might also lead an observer to believe that Chelsea had been trying the kind of attacking drills that Jose Mourinho notoriously eschewed, but dressing room sources indicate that has not really been the case.

In fact, the rush of fixtures since Hiddink took over has left little time to develop intricate new tactics. But there has been one significant change of note: Chelsea attackers aren't bogged down with the many defensive responsibilities they had under Mourinho.

Guus Hiddink's less regimented approach seems to be working in the short term at Chelsea.

Mourinho is a tactical master, but it says much about his approach that when he was asked to describe his ideal No. 10 -- perhaps the most mythic role in the game and traditionally the source of a team's creativity -- he talked as much about the defensive side of the role as the attacking. He even went so far as saying "a No. 10 for me is an eight-and-a-half when the team loses the ball."

Bear in mind this was Mourinho's "ideal." Hiddink's ideal has no such restraints for attackers, as he revealed after the win over Palace. "I don't like to see a team drop back very far, to seek false security, but to look forwards, to get the ball as soon as possible.

"Because when they get the ball, they know how to play. We don't need to add a lot to the quality of players. They are blessed by nature with big quality... on top of that fundamental foundation, they can explore their qualities."

Right now, Chelsea's attackers are allowed to spend more time thinking about attacking than defending, and it has led to a natural lift in performance.

Of course, there's also the psychological lift they get from playing under a different manager.

This recent increase in movement has led to a lot of talk about whether the Chelsea side "downed tools" on Mourinho, but that is somewhat unfair because the situation was far more complex than that. The majority of the Chelsea squad had turned against Mourinho, but some of those who most wanted him out stayed on good form while some of those most with him -- namely Fabregas and Costa -- suffered awful form.

Chelsea's attack appeared reborn vs. Crystal Palace as the likes of Oscar were allowed freedom to create.

That trend indicates that this turnaround is not as simple as players just turning it on now. Sources have told ESPN FC that Mourinho ultimately accepted he would be sacked because he tried everything and nothing worked. Once a new manager came in, it offered a change of scene that, when combined with fewer defensive responsibilities, has naturally released the attackers.

Hiddink's personality has helped, too. As one source says, "he gives the side a 'granddad feeling' and is warm and supporting." The Brazilian core, who were among those most against Mourinho, are also said to love Hiddink.

It remains to be seen whether the team can stay so effective for the rest of the season, especially since it's been a long time since Hiddink has had anything close to success in a full-time role. Whether he takes a more hands-on approach in attack will also be telling.

For the moment, though, Chelsea look to be back on track.

Miguel Delaney covers the Premier League and Champions League for ESPN FC. Twitter: @MiguelDelaney.